1. Field of Invention
The present general inventive concept relates to electrical cords, and, more particularly, to an electrical cord having plugs with improved safety features, such as for example a replaceable and structurally reinforced ground pin and/or one or more indicator lights indicating various states of electrical activity of the cord.
2. Description of the Related Art
In the United States, standard electrical plugs for an electrical power cord have either two or three pins which are configured to be received by corresponding sockets of an electrical outlet to establish an electrical current path to provide electrical current to power an electronic load device. In a two-pin plug, one pin is live and carries current from the source to the load device. The other pin is neutral and returns the current from the load device to the source. A three-pin plug is similar to a two-pin plug in that it includes a live pin, or “blade,” and a neutral blade. However, a three-prong plug also includes a ground pin, the purpose of which is to connect the load device to a grounded electrical path. Thus, the ground pin serves to protect the load device against electric shock due, for example, to insulation failure. The ground pin, when connected to a grounded path, also limits the build-up of static electricity on parts of the device.
A three-pin plug may provide many advantages over a two-pin plug. However, in order to properly utilize a three-pin plug, an electrical outlet having three sockets corresponding to the three pins of the three-pin plug is required. Often, it is necessary or desirable to plug a three-pin plug into an electrical outlet having only two sockets, of the type specifically designed for use with a two-pin plug. In such situations, many users of electrical devices may use a so-called “ground lifting plug,” which is an electrical plug adapter that essentially consists of a three-socket receptacle on one side, and a two-pin plug on the other side. However, it is also not uncommon for a user to simply bend, break off, or otherwise remove, a ground pin from a three-pin plug in order to allow the remaining two pins to fit into a two-socket receptacle of an outlet.
In several situations, such as for example in commercial settings and/or on construction sites, the practice of damaging or removing a ground pin from a three-pin plug and then subsequently using the plug is prohibited by various rules, ordinances, or laws. For example, in a construction setting, use of an extension cord or other power cord having a missing or damaged ground pin is prohibited by the rules of the Occupational Safety and Health Administration (“OSHA”). Accordingly, if a worker on a construction site damages or removes a ground pin on an extension cord having a three-pin plug, it becomes necessary to replace or repair the pin, or to replace the extension cord, often at significant burden and expense. Additionally, construction sites, businesses, and the like are often subjected to various administrative and governmental inspections in which, among other things, electrical plugs and/or cords may be inspected to ensure the plug includes a properly functioning ground pin and that the cord is capable of being properly grounded. Such inspections are often time consuming and can result in costly and burdensome delays to the normal operations of the construction site or business.
Additional disadvantages are associated with the use of power cords having damaged or removed ground pins. For example, many electronic load devices, such as various types of power tools, medical devices, household electronic devices, etc., are designed to operate with the current powering the device running in a specific “polarity,” that is, in a specific direction along the power circuit. More specifically, these devices are typically designed to operate with current running from the live wire of the power cord, through the device, to the neutral wire. In many such devices, exposing the device to “reversed polarity,” that is, current flowing backward along the intended circuit path; i.e., from the neutral wire of the power cord, backward through the device, to the live wire; can result in improper function and/or damage to the device. Thus, when an extension cord is used to connect such devices to an outlet of an electrical source, it is important to ensure that the extension cord is connected to the electrical source in the proper polarity. In other words, it is important that the live blade of the extension cord plug is received within the live socket of the electrical outlet and the neutral blade of the extension cord plug is received within the neutral socket of the electrical outlet.
In the case of the above-discussed extension cords employing three-pin plugs, one additional function of the ground pin is to ensure that the extension cord is plugged into an electrical outlet in the proper polarity. With the ground pin of the three-pin plug of the extension cord intact, the three-pin plug will only fit into the sockets of the electrical outlet in one orientation, that is, with the extension cord plug in the proper polarity. However, when the ground pin of the three-pin plug is damaged or removed, it is possible for the orientation of the plug to be inverted, such that the live blade of the extension cord plug is received within the neutral socket of the electrical outlet and the neutral blade of the extension cord plug is received within the live socket of the electrical outlet. In this orientation, the polarity of the extension cord is reversed, and if an electronic load device is then plugged into the reversed polarity extension cord, it is possible that the electronic load device may be exposed to reversed polarity current.
Additional circumstances can arise in which an electronic load device may be inadvertently exposed to reversed polarity current. For example, if an electrical outlet is incorrectly wired in such a manner that the outlet itself receives reversed polarity current, that is, if the outlet is wired such that the neutral socket of the electrical outlet is in electrical communication with a live wire of a current source and the live socket of the electrical outlet is in electrical communication with a neutral wire of the current source, an extension cord which is plugged into the outlet in a proper orientation may nonetheless be subjected to reversed polarity current. Likewise, an electrical panel, circuit breaker receptacle, or other such device configured to supply electrical current to the outlet may be improperly wired to allow reversed polarity current to the outlet. Thus, in the use of extension cords and other power cords, there is a risk associated with subjecting an electronic load device to reversed polarity current.
In light of the above, there is a need for an electrical cord incorporating a three-pin plug having an improved ground pin, in which the ground pin is easily replaced, and in which the ground pin is constructed to exhibit improved strength over prior art devices, such that the ground pin is difficult to damage or break. There is a further need for an electrical cord incorporating a three-pin plug having an improved ground pin, in which the plug provides a readily-identifiable signal indicating a condition of the plug in which the ground pin may have become damaged or broken, or in which the cord is not capable of being properly grounded. There is a further need for an electrical cord in which the plug provides a readily-identifiable signal indicating a condition of the electrical cord in which the polarity of current supplied to the cord is reversed.